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My 2013 S550 4Matic threw a fault code of P2099 tonight. I've done some googling but the information I found are too generic and I just wanted to ask experts here if there's any particular problem or area to look for on this engine(M278) regarding this issue. One side note is this same code was present about a few months ago which I cleared using a diagnostic tool. The reason I cleared it was because I wanted to make sure the problem really existed and it did not come back till a few months later. I haven't noticed any abnormal behavior from the car.
The code reads as "P2099: Post Catalyst Fuel Trim System Too Rich Bank 2" and second code is "U0402: Invalid Data Received From TCM"
I am hoping it's something I can try to fix myself... Thank you so much in advance for any input.